Kinda the differentiator: if you mostly care about how fast and how far you are going, get the Bolt. It is lighter and more aerodynamic, but not as useful as a map display/routing/ integrate other info type device.

If you mostly want to have maps and directions and other display info (like the radar already mentioned) up on the display, go for the Elemnt or the Roam. I now have the Roam, I'd say get that if you can afford it, the Elemnt if you want to save money. My original Elemnt is now on my wife' s bike, I like the Roam for the color display and it has some (not very sophisticated or reliable yet) re-reouting capability.